Is it worth bothering with supply work, these days?

Is it really worth bothering, trying to get supply, or any teching work, these days? Both agencies and schools seem to have descended to dispicable depths in their treatment of supply teachers. For instance:
1) Being sent to jobs that are then cancelled, leaving you with travelling costs.
2) Wanting repeated CRB forms for every school to which you get sent.
3) Being told that you will have a full day when you are only needed for a hour or so.
4) Being told that you will be paid as a teacher, only to be paid at CS rates.
5) Schools refusing to pay you because of some ridiculous and fabricated 'incident', such as 'you did not stick to the 'non-existant0 cover work'.
6) Being sent to schools miles away, so that transport cost negate any earnings.
I could go on. So far, I have yet to make any profit on agency work; all of it has gone on on unecessary fares.

"Being told that you will be paid as a teacher, only to be paid at CS rates" Does this not count as a verbal contract and, as such, is enforcable in law. Although you won't get any more work through the sodomising agency it might make them sit up and take notice in future. Ditch the illegitimates.

I was almost getting ready to give up when I managed to get two days this week, in decent schools and at a very decent rate of pay.
Whether or not I get any more is to be seen, but it's a start so don't give up yet. Try other agencies, they aren't all bad.